摘要Background:Regulatory B cells(Bregs)is an indispensable element in inducing immune tolerance after liver transplantation.As one of the microRNAs(miRNAs),miR-29a-3p also inhibits translation by degrad-ing the target mRNA,and yet the relationship between Bregs and miR-29a-3p has not yet been fully explored.This study aimed to investigate the impact of miR-29a-3p on the regulation of differentiation and immunosuppressive functions of memory Bregs(mBregs)and ultimately provide potentially effective therapies in inducing immune tolerance after liver transplantation.Methods:Flow cytometry was employed to determine the levels of Bregs in peripheral blood mononu-clear cells.TaqMan low-density array miRNA assays were used to identify the expression of different miRNAs,electroporation transfection was used to induce miR-29a-3p overexpression and knockdown,and dual luciferase reporter assay was used to verify the target gene of miR-29a-3p.Results:In patients experiencing acute rejection after liver transplantation,the proportions and im-munosuppressive function of mBregs in the circulating blood were significantly impaired.miR-29a-3p was found to be a regulator of mBregs differentiation.Inhibition of miR-29a-3p,which targeted nuclear factor of activated T cells 5(NFAT5),resulted in a conspicuous boost in the differentiation and immuno-suppressive function of mBregs.The inhibition of miR-29a-3p in CD19+B cells was capable of raising the expression levels of NFAT5,thereby promoting B cells to differentiate into mBregs.In addition,the observed enhancement of differentiation and immunosuppressive function of mBregs upon miR-29a-3p inhibition was abolished by the knockdown of NFAT5 in B cells.Conclusions:miR-29a-3p was found to be a crucial regulator for mBregs differentiation and immunosup-pressive function.Silencing miR-29a-3p could be a potentially effective therapeutic strategy for inducing immune tolerance after liver transplantation.